1. Field of the Invention
The present invention relates to a damping apparatus for reciprocating pneumatic tools, and more particularly to a damping apparatus for reciprocating pneumatic tools that can dissipate impact during recoil generated by the reciprocating movement in a pneumatic tool.
2. Description of Related Art
Reciprocating pneumatic tools are used to crush stones or break hard objects. With reference to FIGS. 6 and 7, a reciprocating pneumatic tool generally has a cylinder (30), a bi-directional valve (40), a gun-shaped body (50) and a piston (60). The cylinder (30) has a front opening (not numbered) and a rear end (not numbered), and a channel (31) is defined longitudinally through the rear end of the cylinder (30) to communicate with the front opening in the cylinder (30). The front opening in the cylinder (30) is adapted to hold a tool head (70) that is used to break hard objects or the like. The piston (60) is slidably mounted in the channel (31) and is pushed by compressed air to impact the tool head (70).
The rear end of the cylinder (30) is screwed into the gun-shaped body (50) with the bi-directional valve (40). The gun-shaped body (50) includes a top holder (51) and a handle (52). The rear end of the cylinder (30) is screwed into the top holder (51), and the bi-directional valve (40) is attached to the rear end of the cylinder (30) in the top holder (51). To create a reciprocating movement of the piston (60) in the channel (31), the flow of the compressed air in the channel (31) must be bi-directional. A return airway (32) is defined longitudinally in the cylinder (30) through the rear end and communicates with the channel (31) near the front opening of the cylinder (30). Two exhaust ports (33) are defined centrally in the cylinder (30) between the front opening and the rear end of the cylinder (30).
Besides providing means to hold the reciprocating pneumatic tool, the handle (52) is adapted to guide compressed air into the holder (51). The compressed air will flow into the channel (31) via the bi-directional valve (40). The bi-directional valve (40) has inlets (41), a forward outlet (42), a return outlet (42xe2x80x2) and a disk (43) and is attached to the rear end of the cylinder (30) in the holder (51). The forward outlet (42) communicates with the channel (31), and the return outlet (42xe2x80x2) communicates with the return airway (32). The disk (43) is movably mounted between the two outlets (42, 42xe2x80x2) and selectively covers one of the outlets (42, 42xe2x80x2) at a time.
With reference to FIG. 6, the piston (60) is at rest and the disk (43) covers forward outlet (42) to the channel (31). When the compressed air flows through the inlets (41) into the bi-directional valve (40), the compressed air will flow into the channel (31) via the return airway (32) to force the piston (60) to move toward the bi-directional valve (40). When the piston (60) moves past the exhaust ports (33), the piston (60) will compress the air in the channel (31) between the piston (60) and the bi-directional valve (40). The compressed air pushes the disk (43) that closes the return outlet (42xe2x80x2) in the bi-directional valve (40).
With reference to FIG. 7, the compressed air will flow into the channel (31) via the forward outlet (42) when the disk (43) covers the return outlet (42xe2x80x2). The piston (60) is pushed forward by the compressed air and impacts the tool head (70). Similarly, the movement of the piston (60) compresses the air in the channel (31) between the piston (60) and the tool head (70) and the air flow into the return airway (32) pushes the disk (43) to cover the forward outlet (42) in the bi-directional valve (40).
Consequently, the piston (60) will repeatedly impact the tool head (70) to break hard objects. However, the piston (60) will also impact the bi-directional valve (40) during the return. Impact energy created by the piston (60) will be transmitted to the handle (50) and cause vibrations and shock in the pneumatic tool. The user operating the reciprocating pneumatic tool will feel uncomfortable because of the vibrations and shock. After extensive use, the user will feel fatigued and may suffer a chronic injury by the vibrations and shock.
To overcome the shortcomings, the present invention provides a damping apparatus for a pneumatic toll to absorb and dissipated the impact energy during the return to mitigate or obviate the aforementioned problems.
The main objective of the invention is to provide a damping apparatus for a reciprocating pneumatic tool to absorb and dissipate impact energy during the return such that the pneumatic tool is comfortable to be held when breaking hard objects.